Of the six known candidates on San Diego’s head coach radar, only Seahawks coordinator Gus Bradley, 46, and former Bears coach Lovie Smith, 54, have defensive backgrounds.

They interviewed Thursday and Friday, respectively.

Whisenhunt, 50, visited Chargers Park on Saturday. He was the Steelers’ offensive coordinator from 2004 to 2006 before head coaching the Cardinals the past six seasons.

Gruden came Sunday.

The 45-year-old has been the Bengals offensive coordinator since 2011 and is the younger brother of Jon Gruden, ESPN broadcaster and former NFL coach. Jay Gruden drew head coach consideration last year, but he chose not to run, denying interview requests from the Jaguars and Colts.

Telesco was Indianapoilis’ director of player personnel at the time.

Monday’s interview with McCoy, 40, comes two days after the Broncos’ double-overtime loss to the Ravens. He began coaching in the league in 2000, serving as the Panthers’ offensive assistant, wide receivers coach, quarterbacks coach and passing coordinator at different times over a nine-year tenure.

A native of Novato, Calif., he was the Broncos’ quarterbacks coach in 2009 and their coordinator in the three years since. In 2012, Denver scored the NFL’s second most points with the fourth most yards. The year prior, McCoy retooled his offense midseason around the strengths of quarterback Tim Tebow en route to a division title.

Arians, 60, recently completed a 9-3 run as the Colts’ interim head coach. He’s been the offensive coordinator for the Browns (2001 to 2003), Steelers (2007 to 2011) and Colts (2012 to present).

Arians interviewed Sunday in Chicago and will visit Philadelphia on Tuesday.

Telesco said last week Arians did an “amazing job in Indianapolis.”

If the Chargers do ultimately hire a head coach with an offensive background, the chances would seem to increase the current defensive staff will remain largely, if not entirely, in tact.

John Pagano had a strong first season as defensive coordinator while linebackers coach Joe Barry and secondary coach Ron Meeks have NFL coordinator experience.

"I've only been through one coaching change, and the whole defensive staff stayed in tact," Chargers linebacker Jarret Johnson said recently. "I can see that happening here, but you never know. Sometimes, coaches get fired, and the new guy cleans house."